Memory Devices and Methods of Manufacture Thereof

ABSTRACT

Representative methods of manufacturing memory devices include forming a transistor with a gate disposed over a workpiece, and forming an erase gate with a tip portion extending towards the workpiece. The transistor includes a source region and a drain region disposed in the workpiece proximate the gate. The erase gate is coupled to the gate of the transistor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/715,641 filed on 14 Dec. 2012, entitled “Memory Devices and Methodsof Manufacture Thereof,” which application is hereby incorporated hereinby reference.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cell phones, digital cameras, and otherelectronic equipment, as examples. Semiconductor devices are typicallyfabricated by sequentially depositing insulating or dielectric layers,conductive layers, and semiconductive layers of material over asemiconductor substrate, and patterning the various material layersusing lithography to form circuit components and elements thereon.

Memory devices are one type of semiconductor device. Memory devicestypically include an array of memory cells, with each memory cell beingadapted to store digital information or data as a “1” or “0”. Somememory devices are referred to as volatile memories because of theirneed to be refreshed to retain the data, while others are referred to asnon-volatile memories (NVMs) because they do not require refreshing.

A recent development in NVMs is multiple-time programmable (MTP) NVMs,which are programmable multiple times. In comparison with high densityNVM (such as flash memories or E2PROMS), MTP memories are suitable forlow density applications, and are usually characterized by a largermemory cell size and a lower number of masking operations required tomanufacture the memory cells.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a cross-sectional view of a memory device inaccordance with some embodiments;

FIG. 2 shows a top view of a memory device and a schematic of the memorydevice in accordance with some embodiments;

FIG. 3 shows a top view of a memory device in accordance with otherembodiments;

FIG. 4 is a schematic of a memory device in accordance with otherembodiments;

FIGS. 5 through 8 are cross-sectional views of a memory device atvarious stages of manufacturing in accordance with some embodiments;

FIGS. 9 through 12 illustrate cross-sectional views of a memory deviceat various stages of manufacturing in accordance with other embodiments;

FIG. 13 is a cross-sectional view of a memory device in accordance withsome embodiments after the manufacturing steps shown in FIG. 8 or FIG.12; and

FIG. 14 is a flow chart illustrating a method of manufacturing asemiconductor device in accordance with some embodiments.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of some of the embodiments of the presentdisclosure are discussed in detail below. It should be appreciated,however, that the present disclosure provides many applicable inventiveconcepts that can be embodied in a wide variety of specific contexts.The specific embodiments discussed are merely illustrative of specificways to make and use the disclosure, and do not limit the scope of thedisclosure.

Some embodiments of the present disclosure are related to memory devicesand methods of manufacturing thereof. Novel designs and structures ofmemory devices comprising MTP NVMs will be described herein.

Referring first to FIG. 1, there is shown a cross-sectional view of asemiconductor device comprising a memory device 100 in accordance withsome embodiments. The memory device 100 includes a transistor 104 havinga source region S and a drain region D formed in a workpiece 102. Thetransistor 104 comprises a sense transistor including a floating gate114 that is adapted to store a data state indicative of a “1” or “0” insome embodiments, for example. The memory device 100 also includes afirst capacitor 106 comprising an erase gate and a second capacitor 108comprising a coupling gate. The gate 114 of the transistor 104 isintegrally connected the erase gate. The gate 114 of the transistor 104is also integrally connected the coupling gate. A semiconductivematerial 110 is disposed over an insulating material 112 that isdisposed over the workpiece 102. The semiconductive material 110includes the gate 114 of the transistor 104, a plate 116 of the firstcapacitor 106, and a plate 118 of the second capacitor 108. The sourceregion S and the drain region D of the transistor 106 are disposed inthe workpiece 102 proximate the gate 114; e.g., proximate opposite sidesof the gate 114.

A portion of the workpiece 102 comprises a channel region 124 of thetransistor 104, wherein the channel region 124 is disposed between thesource region S and the drain region D. The source and drain regions Sand D may comprise n+ regions formed in the workpiece 102 in someembodiments. Another portion of the workpiece 102 comprises a plate 126of the first capacitor 106, and yet another portion of the workpiece 102comprises a plate 128 of the second capacitor 108. Plates 126 and 128may comprise implantation regions implanted with dopant materials, suchas n-type dopants, as an example. Plates 126 and 128 comprise cell erasecapacitor and cell coupling capacitor regions, respectively, in someembodiments, as another example. Alternatively, p-type dopant materialscan be used. The plate 128 of the second capacitor 108 may comprise anextension region 132 comprising a shallower implantation region than theimplantation region of the plate 128 in some embodiments.

Plates 126 and 128 are also referred to herein (e.g., in some of theclaims) as first plates, and plates 116 and 118 are also referred toherein as second plates, for example. The second plates 116 and 118 ofthe first capacitor 106 and the second capacitor 108, respectively, arecoupled to the gate 114 of the transistor 104. The semiconductivematerial 110 comprises a continuous region of a semiconductive materialthat comprises the gate 114 and plates 116 and 118 in some embodiments,for example.

The second plate 116 of the first capacitor 106 includes a novelv-shaped portion 120 in a cross-sectional view that extends towards theworkpiece 102 in some embodiments. The first capacitor 106 comprisingthe erase gate includes a v-shaped portion 120 in the cross-sectionalview that extends towards the workpiece 102, and the erase gate 106 iscoupled at the second plate 116 to the gate 114 of the transistor 104,for example. The v-shaped portion 120 of the second plate 116 of thefirst capacitor 106 facilitates in the erasure of the data state fromthe transistor 104 gate 114, to be described further herein. Thev-shaped portion 120 of the second plate 116 of the first capacitor 106is also referred to herein, e.g., in some of the claims, as a tipportion.

The workpiece 102 includes a region including a v-shaped recess 122 inthe cross-sectional view in some embodiments. The region of theworkpiece 102 including the v-shaped recess 122 comprises a region thatthe first capacitor 106 is formed in. The v-shaped recess 122 is alsoreferred to herein as a recessed region of the workpiece 102 and a tiprecess, e.g., in some of the claims. The v-shaped portion 120 of thesecond plate 116 of the first capacitor 106 extends towards the recessedregion 122 of the workpiece 102 in some embodiments. The v-shapedportion 120 of the first capacitor 106 comprising the erase gate extendstowards the recessed region 122 of the workpiece 102, for example.

The v-shaped portion 120 of the second plate 116 of the first capacitor106 extends into the recessed region 120 of the workpiece 102 in someembodiments. The v-shaped portion 120 of the first capacitor 106comprising the erase gate extends into the recessed region 122 of theworkpiece 102, for example. The v-shaped portion 120 of the second plate116 of the first capacitor 106 comprising the erase gate extends to alevel that is below the level of a bottom surface 134 of the floatinggate 114 by about 150 to 3,000 Angstroms in some embodiments, forexample. Dimension d₁ comprising the height of the v-shaped portion 120comprises about 50 to 3,000 Angstroms in some embodiments, for example.Alternatively, the v-shaped portion 120 of the second plate 116 of thefirst capacitor 106 comprising the erase gate may extend by an amountbelow the bottom surface 134 of the floating gate 114 comprising otherdimensions.

The erasure and programming of the memory cell 100 are shown at 136 and138, respectively, which will be described further herein.

FIG. 2 shows a top view of a memory device 100 and a schematic 140 ofthe memory device 100 in accordance with some embodiments. FIG. 3 showsa top view of a memory device 100, and FIG. 4 is a schematic 140 of amemory device 100, in accordance with other embodiments.

Referring again to FIG. 2, the transistor 104 in the top view of thememory device 100 is aligned alongside the transistor 104 of theschematic 140. Likewise, the first capacitor 106 and the secondcapacitor 108 are aligned alongside the first capacitor 106 and thesecond capacitor 108 of the schematic 140, respectively. Thesemiconductive material 110 has a greater length L_(EG)' for the secondplate 118 of the second capacitor 108 than the length L_(EG) of thesecond plate 116 of the first capacitor 106 in the embodiments shown inFIG. 2. The length L_(EG) of the second plate 116 of the first capacitor106 comprises about 1 μm or less in some embodiments, as an example. Insome embodiments, length L_(EG) comprises about 0.5 μm, as anotherexample. Length L_(EG)' of the second plate 118 of the second capacitor108 is about 2× (i.e., twice) the length L_(EG) of the second plate 116of the first capacitor 106, in some embodiments. In some embodiments,length L_(EG)' comprises about 1.2 μm, as another example. The length ofthe cell L_(cell) (i.e., the length of the gate 114 of the transistor104) is substantially the same as the length of the second plate 116 ofthe first capacitor 106 in some embodiments. Alternatively, lengthsL_(EG), L_(EG)', and L_(cell) may comprise other dimensions or otherrelative dimensions.

The width W_(EG) of the first plate 126 of the first capacitor 106comprises about 1 μm or less in some embodiments, as an example. In someembodiments, width W_(EG) comprises about 0.5 μm, as another example.The width W_(CG) of the first plate 128 of the second capacitor 108comprises about 1 μm or less in some embodiments, as an example. In someembodiments, width W_(CG) is substantially the same as or less than thewidth W_(EG) of the first plate 126 of the first capacitor 106, asanother example. In some embodiments, width W_(CG) comprises about 0.35μm, as another example. The width W_(cell) of the transistor 104 activearea (e.g., the region of the workpiece 102 disposed under the gate 114)comprises about 2 μm or less in some embodiments, as an example. In someembodiments, width W comprises about 0.8 m, as another example.Alternatively, widths W_(EG), W_(CG), and W_(cell) may comprise otherdimensions or other relative dimensions.

Contacts and/or vias 142 are coupled to various portions of the memorydevice 100, such as the first plates 126 and 128 of the first and secondcapacitors 106 and 108, respectively, and the workpiece 102, to provideelectrical connections to the memory device 100, as shown in FIG. 2.Contacts and/or vias 142 are also coupled to the source and drainregions S and D and gate 114 of the transistor 104 (and thus, also tothe second plates 116 and 118 of the first and second capacitors 106 and108, respectively), not shown. The contacts and/or vias 142 areelectrically coupled to conductive lines, contact pads, and/or terminalsin subsequently formed upper metallization levels of the memory device100, for example, also not shown.

An upper portion of the v-shaped region 120 of the second plate 116 ofthe first capacitor 106 comprises a length L and a width W in a topview, wherein length L and width W comprise about 0.5 μm or less in someembodiments. A lower portion of the v-shaped region 120 of the secondplate 116 proximate a point of the v-shaped region 120 comprises adimension ranging from about 0.1 to about 0.2 μm in some embodiments.Alternatively, the dimensions L, W, and the lower pointed portion of thev-shaped region 120 may comprise other values.

The v-shaped region 120 is sown as square in the top view of FIG. 2.Alternatively, the v-shaped region 120 may comprise other shapes in atop view. The v-shaped region 120 may comprise a rectangle, circle,oval, triangle, trapezoid, octagon, other geometric shapes, otherasymmetric or symmetric shapes, or other shapes in a top view, not shownin the drawings.

FIG. 3 shows a top view of a memory device 100 in accordance with otherembodiments, wherein the semiconductive material 110 comprisessubstantially the same length for the entire width of the semiconductormaterial 110 in these embodiments. For example, lengths L_(EG), L_(EG)',and L_(cell) are substantially the same in the embodiments shown in FIG.3. Widths W_(CG) and W_(cell) are substantially the same and are greaterthan width W_(EG).

The schematics 140 shown in FIGS. 2 and 4 illustrate the electricalconnections and functions of the various components of the memorydevices 100 described herein. The capacitors 106 and 108 are coupled inseries, each with a second plate 116 and 118, respectively, coupled tothe gate 114 of the transistor 104. A voltage terminal V_(CG) is coupledto the first plate 128 of the second capacitor 108, and a voltageterminal V_(EG) is coupled to the first plate 126 of the first capacitor106. A voltage terminal V_(S) is coupled to the source region S, and avoltage terminal V_(D) is coupled to the drain region D of thetransistor 104. A voltage terminal V_(sub) is also coupled to theworkpiece 102 (see FIG. 1) in some embodiments, not shown in theschematic 140. The voltage terminals V_(CG), V_(EG), V_(S), V_(D), andV_(sub) may comprise conductive lines, contact pads, and/or terminals inupper levels of the memory device 100 that are coupled to the variousregions of the memory device 100 using the contacts and/or vias 142shown in the top views in FIGS. 2 and 3, for example.

The memory devices 100 described herein comprise multiple-timeprogrammable (MTP) non-volatile memory (NVM) cells or devices. Theoperation of the memory devices 100, which includes erasing,programming, and reading the memory devices 100 will next be described.Referring again to FIG. 1, the memory device 100 is erasable using thefirst capacitor 106. The v-shaped portion 120 of the second plate 116 ofthe first capacitor 106 comprises an erase tip in some embodiments, forexample. The gate 114 of the transistor 104 is adapted to store a bit ofinformation, and the bit of information is erasable using the erase tip120 of the second plate 116 of the first capacitor 106, for example.

In an erase operation, the transistor 104 is erased usingFowler-Nordheim (FN) tunneling by applying a voltage of about 0 volts tothe workpiece 102 (V_(sub)), and to voltage terminals V_(CG), V_(D), andV_(S), and applying a positive voltage of about 7 to 12 volts toterminal V_(EG) (see also schematics 140 in FIG. 2 and FIG. 4.) Applyingthese voltages causes FN tunneling 136 (see FIG. 1) in the firstcapacitor 106, which erases the negative charge, if present, on thefloating gate 114 of the transistor 104. Any trapped electrons (e⁻)present on the floating gate 114, which is electrically coupled to thesecond plate 116 of the first capacitor 106, migrate through theinsulating material 112 to the first plate 126 of the first capacitor106 due to the FN tunneling 136. The FN tunneling 136 affect pulls theelectrons out of the gate 114. The pointed shape of the v-shaped portion120 of the second plate 116 of the first capacitor 106 advantageouslyreduces the amount of tunneling voltage required to erase the charge onthe floating gate 114 of the transistor 104, for example. The sharppointed tip of the v-shaped portion 120 of the second plate 116 of thefirst capacitor 106 increases the electric field of the FN tunneling 136so that a lower amount of voltage (e.g., the 7 to 12 volts applied tothe voltage terminal V_(EG)) can be used to erase the memory device 100in some embodiments, advantageously. Alternatively, in otherembodiments, the data stored on the transistor 104 may be erased usingother methods, voltages, and voltage terminals.

The floating gate 114 of the transistor 104 is programmable and readableusing the second capacitor 108. The floating gate 114 of the transistor104 is programmable by channel hot electron (CHE) carrier injection 138.First, a convention can be established for a memory array fordetermining a “1” or “0” state of the memory device 100. A programmedtransistor 104 can be established to represent a “1”, and anunprogrammed transistor 104 can be established to represent a “0”. Oralternatively, an unprogrammed transistor 104 can be established torepresent a “1”, and a programmed transistor 104 can be established torepresent a “0”. In either case, a programmed or unprogrammed state ofthe floating gate 114 can be sensed by determining if the floating gate114 is positively (unprogrammed or erased) or negatively (programmed)charged.

In a programming operation, a voltage of about 5 to 8 volts is appliedto voltage terminals V_(CG), V_(EG), and V_(D), and a voltage of about 0volts is applied to voltage terminal V_(S), causing a relatively lowamount of current (e.g., about 1 to 20 μAmperes) to flow through thetransistor 104 from the source region S to the drain region D andmigrate to the floating gate 114. The electrons (e⁻) from the sourceregion S accelerate and become heated due to CHE carrier injection 138,and the electrons migrate through the insulating material 112 to thefloating gate 114 of the transistor 104. The trapped electrons on thefloating gate 114 have a negative charge and lower the potential of thegate 114.

In a read operation, the data stored in the transistor 104 is sensed byapplying a voltage of about 2.3 volts to voltage terminal V_(EG),applying a voltage of about 0.8 volts to terminal V_(D), and applying asweep voltage ranging from about 0 to 2.3 volts to terminal V_(CG)(e.g., each memory cell in an addressed portion of the array is read byapplying a voltage of 2.3 volts to each addressed memory cell) andapplying a voltage of about 0 volts to voltage terminal V_(S) andV_(sub). The drain current indicating the amount of charge stored in thegate 114 of the transistor 104 is detected by a sense amplifier (notshown). If the floating gate 114 is positively charged (e.g.,unprogrammed), the channel region 124 directly beneath the floating gate114 is normally turned on. When a read operation is performed, ifelectrical current flows from the drain region D to the source region S,the memory device 100 is sensed at an erased or unprogrammed state.However, if the floating gate 114 is negatively charged (e.g.,programmed), the region of the channel 124 beneath the floating gate 114is either weakly turned on or is entirely shut off. Thus, when the drainregion D is raised to a read potential of about 0.8 volts, the currentthrough the channel 124 remains either very small or non-existentcompared to the erased state, and the memory device 100 is sensed at aprogrammed state.

Alternatively, in other embodiments, the floating gate 114 of thetransistor 104 of the memory devices 100 may be programmed and/or readusing other methods, voltages, currents, and/or voltage terminals.

FIGS. 5 through 8 are cross-sectional views of a memory device 100 atvarious stages of manufacturing in accordance with some embodiments,wherein an additional masking step and lithography step is used to formthe recessed regions 122 of the workpiece 102. In some embodiments, theSTI regions 130 are first formed in the workpiece 102, and second, thev-shaped recess 122 is formed in the workpiece 102, as shown in FIGS. 5through 8. In other embodiments, the v-shaped recess 122 is first formedin the workpiece 102, and second, the STI regions 130 are formed in theworkpiece 102, not shown in the drawings.

To manufacture the memory device 100, first, the workpiece 102 isprovided. The workpiece 102 may include a semiconductor substratecomprising silicon or other semiconductor materials and may be coveredby an insulating layer, for example. The workpiece 102 may also includeother active components or circuits, not shown. The workpiece 102 maycomprise silicon oxide over single-crystal silicon, for example. Theworkpiece 102 may include other conductive layers or other semiconductorelements, e.g., transistors, diodes, etc. Compound semiconductors, GaAs,InP, Si/Ge, or SiC, as examples, may be used in place of silicon. Theworkpiece 102 may comprise a silicon-on-insulator (SOI) or agermanium-on-insulator (GOI) substrate, as examples.

STI regions 130 are formed in the workpiece 102. The STI regions 130 areformed by etching recesses in the workpiece 102 using an etch process,and filling the recesses with an insulating material 152. The insulatingmaterial 152 may comprise silicon dioxide, silicon nitride, otherinsulators or materials, or combinations or multiple layers thereof.Excess insulating material 152 is removed from over a top surface of theworkpiece 102 using a chemical-mechanical polishing (CMP) and/or etchprocess, as examples, leaving the STI regions 130 comprising theinsulating material 152 formed in the workpiece 102, as shown in FIG. 5.

A masking material 150 is formed over the workpiece 102, as shown inFIG. 6. The masking material 150 comprises a layer of photoresist and/ora hard mask material, as examples. The masking material 150 is patternedwith a desired pattern for the recesses 122 using a lithography process,also shown in FIG. 6, and the workpiece 102 is etched using the maskingmaterial 150 as an etch mask to form the v-shaped recess 122, as shownin FIG. 7. The v-shaped recess 122 comprises a width W at a top portionthereof as previously described herein. The v-shaped recess 122comprises a depth within the workpiece 102 comprising dimension d₂,wherein dimension d₂ comprises about 0.2 μm or less, as an example.Alternatively, dimension d₂ may comprise other values. The maskingmaterial 130 is then removed using an ashing and/or etch process, asshown in FIG. 8.

In the embodiments shown in FIGS. 5 through 8, the STI regions 130 canbe formed before, or after (not shown), the v-shaped recess 122 isformed. For example, to form the STI regions 130 after forming thev-shaped recess 122, in FIG. 6, the masking material 150 can be formedover the workpiece 102 before the STI regions 130 are formed. Theprocessing steps described for FIGS. 6 and 8 are performed, and then theSTI regions 130 are formed. The insulating material 152 of the STIregions (see FIG. 5) is then removed from the v-shaped recess 122 usinga sacrificial or native oxide removal step or an additional lithographyprocess.

FIGS. 9 through 12 illustrate cross-sectional views of a memory device100 at various stages of manufacturing in accordance with otherembodiments, wherein an existing masking step and lithography step isused to form the recessed regions 122 in the workpiece 102. Noadditional lithography masks, etch masks, or lithography processes arerequired in some of these embodiments, advantageously, and the v-shapedrecess 122 is self-aligned, e.g., with the STI regions 130. The STIregions 130 and the v-shaped recess 122 are formed simultaneously inthese embodiments.

The STI regions 130 and the v-shaped recess 122 are formed by forming amasking material 150 over the workpiece 102, as shown in FIG. 9. Themasking material 150 is patterned using a lithography process, formingpatterns for the STI region 130 recesses and also the v-shaped recess122. The patterns are larger for the STI regions 130, and the patternsfor the v-shaped recess 122 comprise a width W. The workpiece 102 isetched using the masking material 150 as an etch mask to form thev-shaped recess 122 and the recesses for the STI regions 130, as shownin FIG. 10. Because the width W of the pattern in the masking material150 for the v-shaped recess 122 is less than the width of the patternsfor the STI regions 130, the recesses for the STI regions 130 are deeperthan the v-shaped recess 122. The masking material 150 is removed, asshown in FIG. 11, and an insulating material 152 is formed over theworkpiece 102. The insulating material 152 fills the v-shaped recess 122and the recesses for the STI regions 130. In some embodiments, theinsulating material 152 also covers the top surface of the workpiece 102as-deposited, not shown. The insulating material 152 is removed fromover the top surface of the workpiece 102 using a CMP process and/oretch process, as shown in FIG. 11. The insulating material 152 isremoved from the v-shaped recess 122, as shown in FIG. 12.

The insulating material 152 is removed from the v-shaped recess 122using a sacrificial or native oxide removal process in some embodiments.In other embodiments, an additional lithography process can be used toremove the insulating material 152 from the v-shaped recess 122, bydepositing another masking material, patterning the masking material toexpose the insulating material 152 in the v-shaped recess 122, and usingan etch process to remove the insulating material 152 from the v-shapedrecess 122, not shown.

FIG. 13 is a cross-sectional view of a memory device 100 in accordancewith some embodiments. After the manufacturing process steps shown inFIG. 8 or FIG. 12, an implantation process (or processes) is used toform the source region S and drain region D of the transistor 104, thefirst plates 126 and 128 of the first and second capacitors 106 and 108,respectively, and the extension region 132 proximate the second plate128 of the second capacitor 108. An insulating material 112 is formedover the top surface of the workpiece 102. The insulating material 112lines the recessed region 122 of the workpiece 102, partially fillingthe recessed region 122 in some embodiments. In other embodiments, theinsulating material 112 completely fills the recessed region 122 of theworkpiece 102, as another example. The insulating material 112 issubstantially conformal in some embodiments, having substantially thesame topography as the workpiece 102 top surface, for example. Theinsulating material 112 comprises silicon dioxide in some embodiments,as an example. The insulating material 112 comprises a thickness ofabout 70 Angstroms or greater in some embodiments. In some embodiments,the insulating material 112 comprises a thickness of about 120 to 130Angstroms, as another example. The insulating material 112 is formedusing an oxidation process in some embodiments. Alternatively, theinsulating material 112 may comprise other materials and dimensions, andother methods may be used to form the insulating material 112.

The semiconductive material 110 is formed over the insulating material112, also shown in FIG. 13. The semiconductive material 110 comprisespolysilicon (poly) having a thickness of about 1,000 Angstroms or morefor example. Alternatively, the semiconductive material 110 may compriseother materials and dimensions.

The semiconductive material 110 is then patterned using lithography toform a desired shape of the gate 114 and second plates 116 and 118 ofthe memory device 100, as shown in FIG. 1 in the cross-sectional view,and as shown in the top views in FIGS. 2 and 3. In some embodiments, theinsulating material 112 is also patterned using the lithography process,as illustrated in FIG. 1. In other embodiments, the insulating material112 is not patterned. The manufacturing process for the memory device100 is then continued, such as forming additional insulating and/orpassivation layers 139 and forming contacts and/or vias 142 (see FIGS. 2and 3) that are coupled to various regions of the memory device 100,such as the plates 126 and 128 of the capacitors 106 and 108, theworkpiece 102, and source region S and drain region D of the transistor140 (and also to the gate 114 of the transistor 104, as another example,not shown).

Only one memory device 100 is shown in the drawings; however, in someapplications, a plurality of the memory devices 100 is manufacturedacross the workpiece 102 simultaneously. The memory devices 100 may bearranged in an array, and word lines and bit lines may be formedproximate the array to access the memory devices 100, not shown in thedrawings. Alternatively, the plurality of the memory devices 100 may bearranged in other shapes, and the memory devices 100 may be addressedusing other methods and structures. Each memory array and any associatedperipheral or support circuitry is singulated from others formed acrossthe workpiece 102.

FIG. 14 is a flow chart 160 illustrating a method of manufacturing amemory device 100 in accordance with an embodiment. In step 162, av-shaped recess 122 is formed in a workpiece 102. In step 164, a firstplate 126 of a first capacitor 106 is formed, a first plate 128 of asecond capacitor 108 is formed, and a source region S and a drain regionD of a transistor 104 is formed in the workpiece 102. The first plate126 of the first capacitor 116 is formed in a region of the workpiece102 including the v-shaped recess 122. In step 166, an insulatingmaterial 112 is formed over the workpiece 102. In step 168, asemiconductive material 110 is formed over the insulating material 112.In step 170, the semiconductive material 110 is patterned to form a gate114 of the transistor 104, a second plate 116 of the first capacitor106, and a second plate 118 of the second capacitor 108.

Some embodiments of the present disclosure include methods ofmanufacturing memory devices 100. Other embodiments include memorydevices 100 manufactured using the methods described herein andincluding the novel v-shaped recesses 122 and v-shaped portions 120 ofthe second plate 116 of the first capacitor 106.

The novel MTP NVM devices 100 described herein have useful applicationin storing program code and/or data on system-on-a chip (SoC)applications, as a substitute for external flash memory devices, orreplacements for read-only memory (ROM) devices, programmable ROM (PROM)devices, erasable PROM (EPROM) devices, electrically erasable PROM(EEPROM) devices, and other types of memory devices, as examples.

Advantages of some embodiments of the disclosure include providing novelmemory devices 100 having a v-shaped erase gate. Novel v-shapedpoly-to-substrate [e.g., (the semiconductive material 110)-to-(the firstplate 126 of the first capacitor 106 formed in the workpiece 102)] erasetips for NVMs are disclosed. The novel memory devices 100 have theability to be erased or programmed at relatively low voltage levels. Thenovel v-shaped erase gates can accomplish erasures at voltage levels ofaround 7 to 12 volts, for example.

In some embodiments, the v-shaped erase gate is self-aligned and anadditional lithography mask and process is not required, which is anadvantage because an additional mask required to create a thin tunnelingoxide is avoided. In other embodiments, one or two additionallithography masks and processes can be used to form the v-shaped recess122, which results in the subsequent formation of a v-shaped portion 120of the second plate 116 of the first capacitor 106 comprising the erasegate.

The pointed tip of the v-shaped portion 120 of the erase gatefacilitates in the erasure of the programming state of the memory device100. Less tunneling voltage is required for the FN tunneling erasefunction due to the pointed erase tip comprising the v-shaped portion120 of the erase gate. The sharp point advantageously creates a higherelectric field during the FN tunneling erasure. The erase tip uses asmall area of the erase gate (e.g., only a portion of the second plate116 of the first capacitor 106), resulting in less layout dependence forcorrect alignment.

The pointed erase tip reduces a potential for over-erase issues byproviding a tip self-stop discharge, due to the pointed shape. This isparticularly advantageous in some applications, because the use of anadditional select gate to overcome such over-erase issues can beavoided. The pointed erase tip also requires less substrate current forerasure of the memory devices 100, providing a more reliable environmentto other circuitry on the semiconductor device. The novel erase tip alsohas improved data retention performance, because the insulating material112 can be thicker for a given erase voltage.

Furthermore, the novel memory devices 100 and manufacturing methodsdescribed herein are easily implementable in manufacturing processflows. In some embodiments, no additional lithography masks orlithography processes are required.

In accordance with some embodiments of the present disclosure, a memorydevice includes a transistor including a gate disposed over a workpiece,and a source region and a drain region disposed in the workpieceproximate the gate. The memory device includes an erase gate including atip portion that extends towards the workpiece. The erase gate iscoupled to the gate of the transistor.

In accordance with other embodiments, a memory device includes a firstcapacitor, a second capacitor coupled in series with the firstcapacitor, and a transistor including a gate coupled to the firstcapacitor and the second capacitor. The first capacitor includes a firstplate disposed in a workpiece, an insulating material disposed over theworkpiece, and a second plate disposed over the insulating material. Thesecond plate of the first capacitor includes a tip portion that extendstowards the workpiece.

In accordance with other embodiments, a method of manufacturing a memorydevice includes forming a tip recess in a workpiece, and forming a firstplate of a first capacitor, a first plate of a second capacitor, and asource region and a drain region of a transistor in the workpiece. Thefirst plate of the first capacitor is formed in a region of theworkpiece including the tip recess. The method includes forming aninsulating material over the workpiece, and forming a semiconductivematerial over the insulating material. The semiconductive material ispatterned to form a gate of the transistor, a second plate of the firstcapacitor, and a second plate of the second capacitor. The tip recesscomprises a v-shape in a cross-sectional view.

In a representative embodiment, a method of manufacturing a memorydevice comprises: forming a tip recess in a workpiece; forming a firstplate of a first capacitor, a first plate of a second capacitor, and asource region and a drain region of a transistor in the workpiece, thefirst plate of the first capacitor being formed in a region of theworkpiece including the tip recess; forming an insulating material overthe workpiece; forming a semiconductive material over the insulatingmaterial; and patterning the semiconductive material to form a gate ofthe transistor, a second plate of the first capacitor, and a secondplate of the second capacitor, wherein the tip recess comprises av-shape in a cross-sectional view, and the second plate of the firstcapacitor includes a tip portion that extends into the tip recess. Themethod may further comprise forming a plurality of shallow trenchisolation (STI) regions in the workpiece; wherein the method comprisesfirst, forming the plurality of STI regions and second, forming the tiprecess; or wherein the method comprises first, forming the tip recess,and second, forming the plurality of STI regions. The step of formingthe tip recess may comprise forming a masking material over theworkpiece, patterning the masking material, etching the workpiece usingthe masking material as an etch mask to form the tip recess, andremoving the masking material. The method may further comprise forming aplurality of shallow trench isolation (STI) regions in the workpiece,and wherein the method further comprises forming the plurality of STIregions and forming the tip recess simultaneously. The steps of formingthe plurality of STI regions and forming the tip recess may compriseforming a masking material over the workpiece, patterning the maskingmaterial, etching the workpiece using the masking material as an etchmask to form the tip recess and recesses for the plurality of STIregions, removing the masking material, forming an insulating materialover the workpiece, removing the insulating material from over a topsurface of the workpiece, and removing the insulating material from thetip recess. The step of patterning the semiconductive material maycomprise forming a substantially continuous region of the semiconductivematerial that comprises the gate of the transistor, the second plate ofthe first capacitor, and the second plate of the second capacitor.

Another representative embodiment of a method of manufacturing a memorydevice comprises: forming a transistor having a gate disposed over asurface of a workpiece, and a source region and a drain region disposedin the workpiece proximate the gate, the source region and the drainregion each extending from the surface of the workpiece into theworkpiece; forming an erase gate including a tip portion that extends ina recess in the workpiece, the recess extending from the surface of theworkpiece into the workpiece, wherein the erase gate directly contactsthe gate of the transistor; and forming a coupling gate over theworkpiece, the coupling gate directly contacting the gate of thetransistor. The step of forming the transistor may comprise integrallyconnecting the gate of the transistor to the erase gate. The method mayfurther comprise disposing an insulating material between the tipportion of the erase gate and the workpiece. The insulating material maycomprise a deposition of the insulating material to a thickness of about70 Å or greater. The step of forming the erase gate may compriseextending the tip portion of the erase gate below a bottom surface ofthe gate of the transistor by about 50 Å to about 3,000 Å. The step offorming the transistor may comprise integrally connecting the gate ofthe transistor to the coupling gate.

In yet another representative embodiment, a method of manufacturingmemory device comprises: forming a conductive electrode on a workpiece,the conductive electrode extending across a first region of theworkpiece, a second region of the workpiece, and a third region of theworkpiece; forming a first capacitor in the first region of theworkpiece, the first capacitor comprising a first electrode in theworkpiece and an erase gate electrode, the erase gate electrode being afirst portion of the conductive electrode on the workpiece, theconductive electrode extending into a recess in the workpiece in thefirst region; forming a transistor in the second region of theworkpiece, the transistor comprising a source/drain region in theworkpiece and a gate, the gate being a second portion of the conductiveelectrode on the workpiece; and forming a second capacitor in the thirdregion of the workpiece, the second capacitor comprising a secondelectrode in the workpiece and a coupling gate electrode, the couplinggate electrode being a third portion of the conductive electrode on theworkpiece. The step of forming the conductive electrode may compriseforming a floating conductive electrode. The method may further comprisedisposing a dielectric layer between the conductive electrode and theworkpiece. The step of forming the first capacitor may comprise formingthe recess to have a v-shaped cross section. The step of forming thefirst capacitor may comprise forming the first electrode in a firstdoped region of the workpiece, and forming the second electrode in asecond doped region of the workpiece. The step of forming the conductiveelectrode may comprise forming an L-shaped cross section of theconductive electrode in a plane parallel to a top surface of theworkpiece. The step of forming the conductive electrode may compriseforming a rectangular shaped cross section of the conductive electrodein a plane parallel to a top surface of the workpiece. The step offorming the first capacitor may comprise extending a tip portion of theerase gate electrode below a bottom surface of the gate of thetransistor by about 50 Å to about 3,000 Å.

Although some embodiments of the present disclosure and their advantageshave been described in detail, it should be understood that variouschanges, substitutions and alterations can be made herein withoutdeparting from the spirit and scope of the disclosure as defined by theappended claims. For example, it will be readily understood by thoseskilled in the art that many of the features, functions, processes, andmaterials described herein may be varied while remaining within thescope of the present disclosure. Moreover, the scope of the presentapplication is not intended to be limited to the particular embodimentsof the process, machine, manufacture, composition of matter, means,methods and steps described in the specification. As one of ordinaryskill in the art will readily appreciate from the disclosure of thepresent disclosure, processes, machines, manufacture, compositions ofmatter, means, methods, or steps, presently existing or later to bedeveloped, that perform substantially the same function or achievesubstantially the same result as the corresponding embodiments describedherein may be utilized according to the present disclosure. Accordingly,the appended claims are intended to include within their scope suchprocesses, machines, manufacture, compositions of matter, means,methods, or steps.

What is claimed is:
 1. A method of manufacturing a memory device, themethod comprising: forming a tip recess in a workpiece; forming a firstplate of a first capacitor, a first plate of a second capacitor, and asource region and a drain region of a transistor in the workpiece, atleast a portion of the first plate of the first capacitor comprising thetip recess; forming an insulating material over the workpiece; forming asemiconductive material over the insulating material; and patterning thesemiconductive material to form a gate of the transistor, a second plateof the first capacitor, and a second plate of the second capacitor,wherein the tip recess comprises a v-shape in a cross-sectional view,and the second plate of the first capacitor includes a tip portion thatextends into the tip recess.
 2. The method of claim 1, furthercomprising forming a plurality of shallow trench isolation (STI) regionsin the workpiece.
 3. The method of claim 2, wherein forming the tiprecess comprises: forming a masking material over the workpiece;patterning the masking material; and etching the workpiece using themasking material as an etch mask to form the tip recess.
 4. The methodof claim 2, wherein forming the plurality of STI regions and forming thetip recess occur simultaneously.
 5. The method of claim 4, whereinforming the plurality of STI regions and forming the tip recesscomprise: forming a masking material over the workpiece; patterning themasking material; etching the workpiece using the masking material as anetch mask to form the tip recess and recesses for the plurality of STIregions; removing the masking material; forming an insulating materialover the workpiece; removing the insulating material from over a topsurface of the workpiece; and removing the insulating material from thetip recess.
 6. The method of claim 1, wherein patterning thesemiconductive material comprises forming a substantially continuousregion of the semiconductive material that comprises the gate of thetransistor, the second plate of the first capacitor, and the secondplate of the second capacitor.
 7. A method of manufacturing a memorydevice, the method comprising: forming a transistor having a gatedisposed over a surface of a workpiece, and a source region and a drainregion disposed in the workpiece proximate the gate, the source regionand the drain region each extending from the surface of the workpieceinto the workpiece; forming an erase gate including a tip portion thatextends in a recess in the workpiece, the recess extending from thesurface of the workpiece into the workpiece, wherein the erase gatecontacts the gate of the transistor; and forming a coupling gatedisposed over the workpiece, the coupling gate contacting the gate ofthe transistor.
 8. The method of claim 7, wherein forming the transistorcomprises integrally connecting the gate of the transistor to the erasegate.
 9. The method of claim 7, further comprising disposing aninsulating material between the tip portion of the erase gate and theworkpiece.
 10. The method of claim 9, wherein disposing the insulatingmaterial comprises depositing the insulating material to a thickness ofabout 70 Å or greater.
 11. The method of claim 7, wherein forming theerase gate comprises extending the tip portion of the erase gate below abottom surface of the gate of the transistor by about 50 Å to about3,000 Å.
 12. The method of claim 7, wherein forming the transistorcomprises integrally connecting the gate of the transistor to thecoupling gate.
 13. A method of manufacturing memory device, the methodcomprising: forming a conductive electrode on a workpiece, theconductive electrode extending across a first region of the workpiece, asecond region of the workpiece, and a third region of the workpiece;forming a first capacitor in the first region of the workpiece, thefirst capacitor comprising a first electrode in the workpiece and anerase gate electrode, the erase gate electrode being a first portion ofthe conductive electrode on the workpiece, the conductive electrodeextending into a recess in the workpiece in the first region; forming atransistor in the second region of the workpiece, the transistorcomprising a source/drain region in the workpiece and a gate, the gatebeing a second portion of the conductive electrode on the workpiece; andforming a second capacitor in the third region of the workpiece, thesecond capacitor comprising a second electrode in the workpiece and acoupling gate electrode, the coupling gate electrode being a thirdportion of the conductive electrode on the workpiece.
 14. The method ofclaim 13, wherein forming the conductive electrode comprises forming afloating conductive electrode.
 15. The method of claim 13 furthercomprising disposing a dielectric layer between the conductive electrodeand the workpiece.
 16. The method of claim 13, wherein forming the firstcapacitor comprises forming the recess to have a v-shaped cross section.17. The method of claim 13, wherein forming the first capacitorcomprises forming the first electrode in a first doped region of theworkpiece, and forming the second electrode in a second doped region ofthe workpiece.
 18. The method of claim 13, wherein forming theconductive electrode comprises forming an L-shaped section of theconductive electrode in a plan view.
 19. The method of claim 13, whereinforming the conductive electrode comprises forming a rectangular shapedsection of the conductive electrode in a plan view.
 20. The method ofclaim 13, wherein forming the first capacitor comprises extending a tipportion of the erase gate electrode below a bottom surface of the gateof the transistor by about 50 Å to about 3,000 Å.